Method of forming a semiconductor device using layered etching and repairing of damaged portions

Abstract

A method of fabricating a semiconductor device includes plasma etching a portion of a plurality of metal dichalcogenide films comprising a compound of a metal and a chalcogen disposed on a substrate by applying a plasma to the plurality of metal dichalcogenide films. After plasma etching, a chalcogen is applied to remaining portions of the plurality of metal dichalcogenide films to repair damage to the remaining portions of the plurality of metal dichalcogenide films from the plasma etching. The chalcogen is S, Se, or Te.

What is claimed is: 
     
       1. A method of fabricating a semiconductor device, comprising:
 plasma etching a portion of a plurality of metal dichalcogenide films comprising a compound of a metal and a chalcogen disposed on a substrate by applying a plasma to the plurality of metal dichalcogenide films, wherein a top metal dichalcogenide film of the plurality of metal dichalcogenide films is formed by:
 depositing a metal film by physical vapor deposition on top of another metal dichalcogenide film; and 
 reacting the metal film with a chalcogen; 
 
 after plasma etching, applying an additional quantity of the chalcogen to remaining portions of the plurality of metal dichalcogenide films to repair damage to the remaining portions of the plurality of metal dichalcogenide films caused by the plasma etching; and 
 wherein after the repair, substantially no metal oxide is on the remaining portions of the plurality of metal dichalcogenide films. 
 
     
     
       2. The method of  claim 1 , wherein the plasma is selected from the group consisting of oxygen, argon, hydrogen, and reactive-ion etch gases. 
     
     
       3. The method of  claim 1 , wherein each one of the plurality of metal dichalcogenide films comprise a metal dichalcogenide selected from the group consisting of WS 2 , MoS 2 , WSe 2 , MoSe 2 , WTe 2 , and MoTe 2 . 
     
     
       4. The method of  claim 1 , wherein the applying the additional quantity of the chalcogen to remaining portions of the plurality of metal dichalcogenide films is a re-sulfurization operation in which evaporated sulfur is applied to the remaining portions of the plurality of metal dichalcogenide films. 
     
     
       5. The method of  claim 1 , further comprising before the plasma etching:
 forming a first metal dichalcogenide film comprising a first metal dichalcogenide on the substrate; and 
 forming a second metal dichalcogenide film comprising a second metal dichalcogenide on the first metal dichalcogenide film to form the plurality of metal dichalcogenide films, 
 wherein the first metal dichalcogenide and the second metal dichalcogenide are different in composition. 
 
     
     
       6. The method of  claim 5 , wherein the plasma etching removes a portion of the second metal dichalcogenide film, thereby exposing a portion of the first metal dichalcogenide film. 
     
     
       7. The method according of to  claim 1 , wherein the plasma is an oxygen plasma, the chalcogen is sulfur, and the applying an additional quantity of the chalcogen to the remaining portions of the plurality of metal dichalcogenide films converts metal oxides formed during the plasma etching to metal sulfides. 
     
     
       8. A method of fabricating a semiconductor device, comprising:
 forming a first metal dichalcogenide film comprising a compound of a first metal and a first chalcogen on a substrate; 
 forming a second metal dichalcogenide film comprising a compound of a second metal and a second chalcogen on the first metal dichalcogenide film; 
 patterning the first metal dichalcogenide film and second metal dichalcogenide film to form a channel region comprising the first and second metal dichalcogenide films; 
 selectively etching spaced-apart portions of the channel region to remove portions of the second metal dichalcogenide film, thereby exposing portions of the first metal dichalcogenide film; 
 applying an additional quantity of the first chalcogen to at least exposed portions of the first metal dichalcogenide film; 
 performing X-ray photoelectron spectroscopy to the exposed portions of the first metal dichalcogenide film to confirm that substantially no metal oxide is on the exposed portions of the first metal dichalcogenide film; 
 depositing a first conductive layer on the exposed portions of the first metal dichalcogenide film; 
 depositing a dielectric layer over the second metal dichalcogenide film and the first conductive layer; and 
 forming a second conductive layer over the dielectric layer. 
 
     
     
       9. The method of  claim 8 , wherein the etching is plasma etching using a plasma and the plasma is selected from the group consisting of oxygen, argon, hydrogen, and reactive-ion etch gases. 
     
     
       10. The method of  claim 9 , wherein a plasma power ranges from about 20 W to about 60 W, and an etching time ranges from about 5 sec. to about 60 sec. 
     
     
       11. The method of  claim 9 , wherein the plasma is an oxygen plasma, the first chalcogen is sulfur, and the applying an additional quantity of the first chalcogen to at least the first metal dichalcogenide film converts metal oxides formed during the plasma etching to metal sulfides. 
     
     
       12. The method of  claim 8 , wherein the first and second metal dichalcogenides are different in composition and are selected from the group consisting of WS 2 , MoS 2 , WSe 2 , MoSe 2 , WTe 2 , and MoTe 2 . 
     
     
       13. The method of  claim 8 , wherein the substrate comprises silicon, silicon oxide, or aluminum oxide. 
     
     
       14. The method of  claim 8 , wherein the applying an additional quantity of the first chalcogen to at least exposed portions of the first metal dichalcogenide film is a re-chalcogenization operation in which evaporated chalcogen is applied to the first metal dichalcogenide film. 
     
     
       15. The method of  claim 8 , wherein the first and second metal dichalcogenide films have a thickness of about 0.5 nm to about 10 nm. 
     
     
       16. A method of fabricating a semiconductor device, comprising:
 forming a first metal dichalcogenide monolayer film comprising a compound of a first metal and a first chalcogen on a substrate by:
 depositing a first metal film of the first metal by atomic layer deposition; and 
 reacting the first metal film with a first chalcogen; 
 
 forming a second metal dichalcogenide monolayer film comprising a compound of a second metal and a second chalcogen on the first metal dichalcogenide monolayer film by:
 depositing a second metal film of the second metal by atomic layer deposition; and 
 reacting the second metal film with a second chalcogen; 
 
 etching the second metal dichalcogenide monolayer film by oxygen plasma to form at least one opening exposing a portion of the first metal dichalcogenide monolayer film; 
 applying a vaporized chalcogen to at least the exposed portion of the first metal dichalcogenide monolayer film; and 
 wherein after the applying the vaporized chalcogen, substantially no metal oxide is on the exposed portion of the first metal dichalcogenide monolayer film. 
 
     
     
       17. The method of  claim 16 , wherein:
 the applying the vaporized chalcogen comprises applying evaporated sulfur. 
 
     
     
       18. The method of  claim 16 , wherein:
 the substrate comprises sapphire, 
 the first metal dichalcogenide monolayer film comprises MoS 2 , MoSe 2 , or MoTe 2 , and 
 the second metal dichalcogenide monolayer film comprises WS 2 , WSe 2 , or WTe 2 . 
 
     
     
       19. The method of  claim 16 , wherein the first and second metal dichalcogenide monolayer films have a thickness of about 0.5 nm to about 10 nm. 
     
     
       20. The method of  claim 16 , wherein a plasma power ranges from about 20 W to about 60 W, and an etching time ranges from about 5 sec. to about 60 sec.